芦山地震地震动上下盘效应研究  

Study of Hanging-wall Effect of Fault in Lushan Earthquake

作　　者：喻畑[1] 赵亚敏[1] 陆鸣[1] 

机构地区：[1]中国地震局地壳应力研究所,北京100085

出　　处：《震灾防御技术》2014年第3期431-438,共8页Technology for Earthquake Disaster Prevention

基　　金：中国地震局地壳应力研究所基本科研业务专项"我国新一代地震动衰减关系研究(ZDJ2013-04)";国家自然科学基金资助项目(51108428)联合资助

摘　　要：2013年4月20日的芦山7.0级地震是继2008年5月12日汶川8.0级特大地震之后,发生在龙门山断裂带上的又一次大震级逆冲型地震。与汶川地震相比,芦山地震的发震断层没有地表出露,断层的滑动角更大,其逆冲性质更强烈。本文挑选了芦山地震中断层距小于200km的45条强震动记录,基于地震动衰减关系进行统计分析,对比了上盘和下盘台站地震动参数相对于衰减关系的对数残差。结果表明:芦山地震的上下盘效应明显,近断层上盘地震动的高频成分要高于同断层距的下盘;上盘地震动衰减要明显快于下盘。地震动衰减关系用简单的一个距离参数很难描述近场断层尺寸效应的影响,也很难模拟地震动上下盘效应。因此,在近场强地面运动模拟中,应多考虑有限断层模型,以模拟断层的尺寸效应。Lushan Ms7.0 earthquake on 20th April,2013 is another thrust fault generated earthquake occurred at Longrnen Mountain Fault Zone after 2008 Wenchuan Ms8.0 earthquake.Compared with Wenchuan earthquake,the rupture of seismogenic fault of Lushan earthquake did not reach the ground,and had a greater rake angle.Based on ground motion attenuation model,this paper we chosen 45 strong motion records with rupture distance less than 200km,to analyze the logarithmic residuals of ground motion data at sites of the hanging wall and the foot wall.The results show that the attenuation model overall underestimate the ground motion at the hanging wall,especially for the high frequency component of ground motion; ground motion in the hanging wall attenuated with increasing rupture distance more quickly than that at the foot wall.A simple parameter,such as rupture distance,is not efficient enough to describe the influence of fault size to the near-fault ground motion attenuation.As a result,we should consider the finite fault model in the near field strong ground motion simulation.

关 键 词：芦山地震 地震动 上下盘效应 衰减关系 

分 类 号：P315[天文地球—地震学]